Recently, the microphotographic recording of a large amount of documents such as checks, bank bills and so on by using rotary type microphotography cameras or the like have been frequently used in general offices such as banks. However, since wet silver salt films are used, it is necessary that the exchange of harmful processing liquid is carried out by general operators within such general offices. Therefore, there has been a strong demand for a system which can eliminate such harmful and complicated process and operations so that the development process can be accomplished in a simple manner.
Meanwhile, dry silver salt films which can be thermally developed to obtain images have been already developed as convenient silver salt film instead of wet silver salt film and used for various purposes. But, since stabilities of raw or unexposed film and developed images are limited, they have not been used in the rotary type microphotography cameras.
A conventional roll film heater comprises in general a rotating heating roller and a nip roller for ensuring the satisfactory intimate contact of the film with the heating roller so as to ensure the heating of the film. Alternatively, a conventional roll film heater comprises a heating roll and a wool yarn soft member adapted to make the film intimately contact with the heating roller. However, in such roll film heaters with the above-described constructions, the stability and quality of images obtained are greatly influenced by thermal developing conditions.
Some patents and reports disclose a process for making a film into very intimate contact with a heating roller by charging the film with static electricity and a method in which a film is caused to float in the air by the heated air so as to heat the film. (For example, see U.S. Pat. No. 3,585,917)
In general, in most conventional wet and rotary type cameras, a wet developing tank and a drying zone are disposed in the lower portion of the camera or an independent developing unit is used. As a result, the conventional rotary type cameras are large in volume and thus there is a problem that a considerably large installation space is required in the offices. In this manner, the conventional rotary type microphotography camera requires a relatively large developing space, contrary to a desire that the camera is designed to be compact in size. Therefore, it has been impossible to make the wet and rotary type camera considerably compact in size, unlike the rotary type camera using thermally developed films. Furthermore, in the case of a camera in which a wet developing tank, a water washing or rinsing tank and a drying zone are disposed in the lower portion of a camera, there has been a problem that a film loss is increased in the start and end portions of the film to be wound. In addition, the exposure and the development process are not carried out at the same speed, so that it is impossible to check a frame by carrying out developing processes simultaneously with the exposure.
The wet silver salt film does not include addition agents such as developing agent inside the film, so that the life of an unexposed wet silver salt film is longer than that of a dry silver salt film. Thus, in the conventional wet silver salt film rotary type camera, unexposed or raw films are stored only in a place shielded from light.
On the other hand, the storage stability of unexposed dry silver salt films is in general not satisfactory. Therefore, when the unexposed dry silver salt film is loaded in the rotary type camera of the type described above, the life of the unexposed film is one or two months at the longest due to the rise in temperature in the camera because a light source is incorporated adjacent to a rolled film and a thermal developing roller or the like is disposed adjacent to the film. As a result, the life of the film cannot be increased to a practically satisfactory period of time.
Furthermore, the wet silver salt film contains in general a reducing agent which reacts with a silver salt oxidizing agent when heated to precipitate metal salts, an adjusting agent for adjusting an amount of silver precipitated during the developing step, a binder acting as a bonding or dispersion agent for the silver-salt oxidizing agent, a thermal antifoggant, a chemical sensitizer, a stabilizing agent and so on which serve to adjust the photographic characteristics. However, during the storage, blooming of such addition agents tends to occur over the surfaces of the film and therefore limits the life of the unexposed film. Furthermore, the blooming deteriorates the picture quality such as resolution.
In view of the above, considerable efforts have been exerted in order to improve the stability of unexposed films and the stability of developed images by changing the compositions of the compounds of non-photosensitive dry silver salts, (for instance, as disclosed in Japanese Laid-Open patent application No. 53-114419 and its corresponding U.S. Pat. No. 4,173,482), but the improvement of the photosensitive materials has substantially reached the limit so that it is difficult to expect a further improvement of the film characteristics only by the improvements of the film compositions. For instance, when it is desired to increase a sensitivity, the stability of unexposed film is adversely affected. When it is tried to improve the stability, the sensitivity is decreased.
Therefore, the present inventors have extensively studied improvements of film from a broader viewpoint not only by improving the compositions of the photosensitive materials but also by changing the conditions under which the films are produced and by studying and introducing novel processes. As a result of such extensive studies and experiments, the inventors have found out various phenomena in the latter half of the film production process which cannot be observed in the conventional dry silver salt photosensitive materials.
For instance, even if various conditions of the production process after the coating of a non-photosensitive dry silver salt compound are slightly varied, the characteristics of the film vary over a considerably large range. Such processing conditions interact with each other in a very complicated way and affects the film characteristics, so that it is extremely difficult to define the ranges in which the conditions can be varied.
Moreover, the improvement of stability and quality of the film only by the improvement of the compositions of the photosensitive materials has now limit so that it is required to develop a camera system best adapted for use with dry silver salt film. That is, the camera system must be reviewed so as to improve its heating roller systems, optical systems and a film storage and rewinding system and furthermore there is the problem of how to monitor the storage conditions of unexposed film and how to control the film storage conditions.